Quantitative 3D Analysis of Levator Ani Muscle Subdivisions in Nulliparous Women: MRI Feasibility Study

Overview

Journal Diagnostics (Basel)

Specialty Radiology

Date 2024 May 11

PMID 38732338

Authors

Nathalie Moser

Stephan Skawran

Klaus Steigmiller

Barbara Rohrnbauer

Thomas Winklehner

Cacilia S Reiner

Cornelia Betschart

Affiliations

Soon will be listed here.

Abstract

Background: The levator ani muscle (LAM) is crucial for pelvic floor stability, yet its quantitative MRI assessment is only a recent focus. Our study aims to standardize the quantitative analysis of the LAM morphology within the 3D Pelvic Inclination Correction System (3D-PICS).

Methods: We analyzed 35 static MR datasets from nulliparous women examining the pubovisceral (PVM), iliococcygeal (ICM), coccygeal (COC), and puborectal muscle (PRM). The PVM consists of three origin-insertion pairs, namely the puboanal (PAM), puboperineal (PPM) and pubovaginal muscle (PVaM). The analysis included a quantitative examination of the morphology of LAM, focusing on the median location (x/y/z) (x: anterior-posterior, y: superior-inferior, z: left-right) of the origin and insertion points (a), angles (b) and lengths (c) of LAM. Inter-rater reliability was calculated.

Results: Interindividual variations in 3D coordinates among muscle subdivisions were shown. In all, 93% of all origin and insertion points were found within an SD of <8 mm. Angles to the xz-plane range between -15.4° (right PRM) and 40.7° (left PAM). The PRM is the largest pelvic muscle in static MRI. The ICC indicated moderate-to-good agreement between raters.

Conclusions: The accurate morphometry of the LAM and its subdivisions, along with reliable inter-rater agreement, was demonstrated, enhancing the understanding of normal pelvic anatomy in young nulliparous women.

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